Nematocysts work by discharging a coiled filament containing toxins, triggered either by physical contact or osmotic pressure changes. This filament punctures the skin and injects venom.
The Mechanism of Nematocyst Action
Nematocysts, also known as stinging capsules, are specialized organelles found in cnidocytes, the stinging cells of cnidarians (e.g., jellyfish, sea anemones, corals). Their function is to capture prey and defend against predators. Here's a breakdown of how they work:
- Triggering: Nematocysts are triggered to discharge in two primary ways, according to the reference:
- Physical Contact: Contact with a foreign body (like prey or a predator) can activate the nematocyst.
- Osmotic Mechanisms: Changes in osmotic pressure can also trigger discharge.
- Discharge: Upon activation, a coiled filament inside the nematocyst rapidly everts (turns inside out). This process is one of the fastest biological events known.
- Penetration: The everted filament is often armed with barbs or spines, allowing it to puncture the skin or exoskeleton of the target.
- Venom Injection: After penetration, the nematocyst injects a complex mixture of toxins into the target. According to the provided reference, this release of toxins causes both local and systemic reactions.
Effects of Nematocyst Venom
The effects of nematocyst venom vary depending on the species of cnidarian and the amount of venom injected. Common effects include:
- Pain: A burning or stinging sensation at the site of contact is typical.
- Inflammation: The affected area may become red, swollen, and itchy.
- Systemic Effects: In severe cases, systemic reactions can occur, affecting the entire body. These may include:
- Muscle cramps
- Nausea and vomiting
- Difficulty breathing
- Cardiovascular problems
